Originally Posted by
muji
Thanks, Andy33.
They'll arrive at T2 on Icelandair, then will have a BA flight a few hours later, from T5, to Dublin.
I'll check with Icelandair to see if they have a baggage agreement with BA (to send the bags from the Icelandair flight to the BA flight), but in the meantime if anyone knows if there is such an agreement in place, please let me know.
Certainly they won't be able to through-check unless they have a baggage interline agreement, but even if they do you need to find out if they actually use it in cases like these. Very many airlines these days won't transfer bags on to another airline unless the passenger is through-ticketed, except in cases of disruption to flights. Others will through-check on to airlines in the same alliance (which doesn't help since Icelandair isn't in OneWorld).
As the UK and Irish Republic are in a Common Travel Area passengers have to pass through immigration in whichever of the two countries they reach first, so anyone connecting in any UK airport for Dublin will always have to clear UK immigration first.
One option would be to change the BA flight from T5 to DUB to a BA codeshare on an Aer Lingus flight, as Aer Lingus use T2 so the distance to move luggage is much reduced.